Marine mammal bycatch: from global to local scale
Bycatch is the act of catching unwanted species in a fishing operation, i.e. all those species that are not the target of the fishery. Some may argue that bycatch is an acceptable consequence of being able to supply the world with wild species of fish and seafood. Often, the associated mortality values are so high that they threaten populations and species. Data indicate that, annually, a minimum of 7.3 million tons of marine life are caught as bycatch.
The problem is aggravated if the bycatch occurs with protected species. Normally the term bycatch is used to refer to those accidental captures of marine mega-fauna species (marine mammals, turtles, sea birds, sharks and other large fish species).
For marine mammals (dolphins, whales, seals, sirenians …) the bycatch is today their main conservation problem. At a global level, if we look at the 10 most threatened marine mammal species, we can observe that those with less than 1500 individuals are affected by different conservation problems such as habitat loss, pollution, boat collisions, intentional deaths, fragmentation of habitat due to water management policies, poaching… but all of these species share a common conservation problem, bycatch with fishing gears.
Due to this accidental capture, species such as the Yangtze dolphin have been declared extinct and the vaquita or California porpoise will probably be extinct during this decade. Two examples of a fishing activity that, despite not seeking its death voluntarily, it has led to it.
Bycatch is not intended to harm these species either directly or indirectly and should be understood as events that occur as a result of chance. However, it should be borne in mind that the impact produced can be very high. Worldwide, it is estimated that 300,000 dolphins are killed in fishing gear each year.
Incidental captures of marine mammals occur mainly for two reasons. One, because they get caught in fishing gear because they did not detect the gear. Two, because they get caught when they have voluntarily gone to take advantage of a food resource provided by the fishing gear. To try to minimize them in the first case, it is necessary to try that the dolphins see and recognize the gear in order to avoid it, and in the second case it is necessary to prevent the dolphins from approaching the gear to feed, and in the case that it cannot be avoided, to see the way that they do not get trapped. There are three ways to address these catches:
- Changes in fishing operations and practices
- Modification and improvement of fishing gear
- Spatial and temporal restrictions and regulations to avoid interaction
Catalonia is not exempt from this global problem. Although with quite different order of magnitude there is also an interaction between dolphins and fishing activity. From SUBMON, and through the project #PescantAmbDofins financed by GALP with FEMP funds, we have created a space of participation where together with the fishermen and the Administration we can find solutions or viable alternatives to minimize the possible captures of protected species that can occur on our coasts. This last week, with a significant presence of fishermen from the fraternities of Roses and Llançà and representatives of the Section of Control and Maritime Affairs of the Ministry of Agriculture, Livestock, Fisheries and Food and the Service of Fauna and Flora of the Ministry of Territory and Sustainability of the Autonomous Government of Catalonia, has begun to work to find a joint solution and the establishment of a protocol that is easy to follow by fishermen. We are very grateful for the willingness of each party. We advance and will continue to inform.